Transporting crew members of ships from the ship to a location off-ship, such as to a nearby oil platform, can be challenging in times of inclement weather. Wave heights of 30-40 feet may be common in the high seas and wind speeds of 30-40 knots can be common, thus making getting on and off ships difficult because the ship may be listing about in relation to any nearby structure.
In the past, helicopters and/or cranes were used to lift and carry baskets that held crew. The crane or helicopter would engage and lift the basket and then carry the basket, with crew in tow, to the destination, e.g., from the ship to the platform. This method, however, is time-consuming and requires many levels of coordination both on and off the ship for arranging for crew members to get on or off the ship.
More recently, gangway techniques have been used wherein a free end of a ramp attached to the deck of a platform may be maneuvered to engage the nearby ship. Such techniques are only suitable for use in relatively low sea states since inclement weather may produce substantial movement of the ramp. Of course, substantial movement of the ramp poses safety risks to any crew members that may be using the ramp at the time.